Zinc base alloy



Patented July 7 21 1936 ZINC BASE ALLOY Willis M. Peirce and Edmund A. Anderson, Palmerton, Pa., assignors to The New Jersey Zinc produce wrought z'inc' products possessing sugated sheets for roofing and siding purposes on 5 perior resistance to cold flow, as well as wrought buildings. Here resistance to cold flow is or great zinc products made from such alloy. importance,'since it determines the gauge of zinc Zinc, like other metals of relatively low melting necessary to give adequate strength and resistjpoint, undergoes slow plastic deformation or, cold ance to plastic d'eformationwhen the sheets are 7 10 flow when subjected continuously to loads as low laid on the building purlins. 10 as a quarter of the ultimate tensile strengthtas Our investigations and experiments have indimeasured by ordinary tensile testing methods. cated that the increase in the resistance to cold All wrought or mechanically worked zinc prodflow which can be secured through solid solution ucts made of high grade or,common zinc metal forming alloying elements, such as cadmium and are readily susceptible to such plastic or progrescopper, is limited, and we. have, therefore,'experil5 sive and permanent deformation under constant mented with alloying elements which introduce and continuously applied loads materially below a separate hardening constituent or constituents the ultimate tensile strength,-a phenomenon into the structure of the ultimate zinc base alloy. frequently designated as cold flow.- In other We have investigated a very large'number of zinc words, at ordinary temperatures, a continuously base alloy combinations in thewrought' form and 20 vmpplied constant load (far below the ultimate ten have found that the resistance to cold flow can sile strength'as determined by ordinary methods) be very substantially increased when the zinc causes permanent deformation .in the heretofore base alloy is of appropriate composition. By zinc available wrought zinc products of commerce. base alloy we mean an alloy consisting principally Under sufliciently low continuous loads the rate of zinc, say, for example, not less than 90% zinc 25 of progressive deformation becomes so smallas and preferably not less than 95% zinc. .to be unmeasurable by known methods, if not The principles involved in the compounding of actually reaching the zero value, and such low zinc base alloys capable of being mechanically or negligible loads may be interpreted as safe worked into wrought products possessing su-, working stresses for these heretofore available perior resistance to cold flow are disclosed in our 30 wrought zinc products when used as structural copending patent application, Serial No. 346,493, materials, for example, in .the form of corrugated filed March 12,- 1929. Briefly, such zinc base sheets. "From the structural engineer's viewalloys contain one (or more) metallic element point, however, these wrought zinc products have present in the alloy in solid solution in the zinc so low a safe working stress, as determined by to a measurable extent-and one.(or more) other 35 actual practical experience, as to seriously remetallic' element present in the alloy in anamount "strict their commercial application. greater than its limit of solid solubility in binary In the production of rolled zinc, either by strip association with zinc at ordinary room tempera- ;rolling .or pack rolling, the properties of the ture, say 20 C. The first element, (present in 40 finished rolled strips or sheets depend upon the solid solution in the zinc) appears to produce a 40 composition of the zinc metal as well asupon the slight increase in the resistance to cold flow of rolling practice. Thus, a high grade zinc metal, the alloy. It may be present in amount exceedsuch as the well-known Horsehead or other high ing its limit of solid solubility in zinc but need grade brands, yields a very soft and ductile strip not necessarily be present in such amount. The

or. sheet under appropriate conditions of rolling. second element forms (alone or combined with 45 On the other hand,'the more common grades of zinc or with the first element) a hardening conzinc metal, such as the well-known Prime Weststituent (or constituents) whose function appears em or other grades of common metal, which are to be to produce a very substantial increase in the natural alloys of zinc, lead and cadmium conresistance to cold flow by hindering slip within taining higher percentages of cadmium than presor between the crystals. The present invention 50 ent in high grade zinc metal, yield when rolled is a species-of the broad invention disclosed and under appropriate conditions a stifler and harder claimed in our copending application and is speproduct than can be obtained from high grade cifically directed to a zinc base alloy conforming zinc metal. to the principles underlying that broad invention. a

The stiffer; strip or sheet rolled from common The zin'c base alloy of the present invention 55 Company,

New Jersey New York, N. -Y., a corporation of No Drawing. Application March 18,1929,

- Serial No. 348,118

This invention relates to zinc base alloys and wrought products made therefrom, and has for its object the provision of an improved zinc base alloy capable of being mechanically worked to 5 Claims. (01. -178) zincm'etal possessesfor certain purposes distinct advantages over the softer product rolled from high grade zinc metal.

For example, one of the uses of rolled zinc is in the fabrication of co'rrucontains nickel as the metallic element present in the alloy in excess of its limit of' solid solubility in binary association with zinc at 20 C. The other metallic element present in the alloy in solid solution in the zinc to a measurable extent may be copper, cadmium, manganese,-and probably other metals, alone or in combination." The nickel may be solely reliedupon for introducin into the alloy the contemplated hardening concess of the first element (e. g. copper) beyond its solid solublityin' zinc or from too large an addition of the second element (e. g. nickel) beyond its solid solubility limit in binary association with zinc at 20 C., may affect the alloy unfavorably in respect to either its mechanical working properties or its resistance to cold flow. It has been our.

I experience, particularly with respect to copper,

' cadmium from 0.05 to 2% and possibly to 5%;

that the best results are usually attained by including in the alloy such a percentage of the first element as goes entirely into solid solution in zinc, which in the case of copper and cadmium is about 1%. On the other hand, satisfactory alloys of the invention may be produced with manganese present, as the first element, considerably in excess of its limit of solid solubility in zinc. Subject to these considerations, we believe that, with appropriate methods of mechanical working, the alloying elements, hereinbefore mentioned, may be present in the alloy within the following limits: nickel from 0.05 to 1%; magnesium (in' conjunction withnickel) from 0.005 to 0.5%; lithium. (in conjunction with nickel) from 0.005 to 0.5%; manganese ,(in conjunction with nickel) from 0.1 to 2%; copper or and manganese (as first element within limit of solid solubility in zinc) from 0.01 to 0.1%. In practice we have secured very satisfactory results with about 0.1% to 015% of nickel, alone or in conjunction with about 0.01% of magnesium, or about 0.05% of lithium, or about 0.4% manganese, as the second element orv elements, in combination with about 1% of copper, or about 0.5%

of cadmium, or about 0.1% (or even up to 0.5%) of manganese, as the first element or elements.

The zinc base alloys of the invention may be compounded in any approved manner Either high grade zinc metal relatively free rom lead and cadmium or lower grade zinc metal containing natural 'or usual amounts of lead and cadmium may be used as the zinc base. The normal lead and iron content of either high grade or common zinc metal does not unfavorably afiect those properties of the alloy with which the invention is particularly concerned.- However, taking all factors into consideration, we have found that the optimum results are ordinarily attained when the zinc base is high grade zinc metal. We have secured unusually satisfactory rollingproperties with alloys in which the zinc base was a very high grade zinc metal containing less than 0.01% total impurities. v

In our investigations, we have used the static tensile strength of a wrought zinc product as a measure of its resistance to cold flow. The static tensile strength may be conveniently measured by applying at-static or dead load to a suitable test specimenand observingthe rate of elongation at intervals over an extended period of'time. A series of such tests made with loads giving varying stresses in pounds per square inch is required for the complete evaluation of the static tensile strength. A similar method for measuring the analogous phenomenon of creep in steelyis described by French in Technological papers of the Bureau of Standards No. 296. Y

The high static tensile strength, and hence the superior resistance, to cold flow, of wrought zinc products made from zinc base alloys of the ,invntion is indicated in the following table. The alloying elements specified are those responsible for the alloys capacity of imparting markedresistance to cold flow to wrought products made therefrom. The balance of each alloy was high grade zinc metal. For the purposes of comparison, the table gives the static tensile strength of similarly wrought zinc products made of high grade and common zinc'metal;

Table X x Resistance to cold flow oi wrought product. Timein Composition oi metal item which wrought product minntesto rpwas made duo'el0% e on gation'undsr .static tensile. load of 10,000 a lbs. per sq. in.

High grade zinc metal al 3,000 Alloy No. l. 1% Cu; 0.1 69,000 Alloy No. 2. 1% Cu; 0.01% Mg, 0 50,000 Alloy No. 3.. 0.55% on; 14,-000

The numerical figures of static tensile strength given in the foregoing table are expressedas the time in minutes required to produce 10% elongation in a standard test specimen at a temperature of 20-25 C. with a dead load calculated to give a stress of 10,000 pounds per square inchon the original section of the test specimen. The

standard, test specimen was -a representative the zinc base alloys are capable of developing under more suitable methods of mechanical working. In general, it may be said that the mechanical working of the zinc base alloy should be so conducted as not to cause any substantial condition of work hardening in the finished wrought product, if the maximum resistance to cold flow is to be developed. Such absence of appreciable .work hardening in the wrought product may advantageously be effected by hot working of the ucts of that superior resistance to cold fiow which zinc base alloyyat temperatures above 175 C.

throughout or during the final stages of the working-treatment, as disclosed in the copending patent application of Willis M; Peirce, SerialNo.

347,195, filed March 14, 1929. Where the me- 7 chanicai working of the zinc base alloy causes any substantial or objectionable condition of work hardening in the resulting wrought product, such condition of work hardening may be removed by the improved method of heat treatment disclosed in the copending patent application of Edmund A. Anderson and Elihu H. Kelton, Serial No. 347,196,

vfiled March 14, 1929. This heat treatment is may be made or-fabricated by any operation involving mechanical working of the zinc base alloy. Thus, the mechanical working may be rolling, drawing, extruding and the like or may be punch-press or forming operations such as drawing, extruding, squirting, spinning, bending, folding, etc. In practice, it frequently happens that a particular mechanical working operation causes a condition of work hardening in the resulting wrought product which unfavorably affects the desired superior resistance to cold flow of the product. In such cases resort may advantageous- 1y be had to the heat treatment described in the aforementioned Anderson and Kelton patent application. This heattreatment-may also be advantageously applied to a wrought zinc product of the invention, irrespective of its condition of work hardening, forthe purpose of improving certain physical properties, s'uchas dynamic ductility, essential to the successful conduct of'varipus subsequent fabricating or forming operations,

such as punch-pressing etc.

The improved zinc products of the invention possess very superiorphysical properties as compared with heretofore commercially available phasized the importance and economic advantages of the superior resistance to cold flow. This property imparts to the products of the invention a safe working stress under a continuously applied load very substantially greater than is possible with any heretofore available wrought zinc product made of the usual commercial grades of zinc metal. The improved physical properties of the zinc products of the invention make them useful in many fields and for many purposes,

where the heretofore available wrought zinc products have not been used, as well as greatly superior to the wrought zinc products which have been heretofore used, such as corrugated zinc roofing and the like.

We claim:

1. A zinc base alloy containingfrom .05 to 2% cadmium, and at least one metal selected from the group consisting of manganese and nickel,

wrought zinc products. We; have already em manganese, and from .005 to .5% magnesium.

substantially all of the balance being zinc.

3. A zinc base alloy containing from .05 to 2% cadmium, from .05 to 1% nickel, and from .005 to .5% magnesium, substantially all of the balance being zinc.-

4. A zinc base alloy containing .05 to 2% cadmium, from .05 to 1% nickel, from .01 to .,1% manganese and from .005 to.5% magnesium, substantially all of the balance being zinc.

5. A zinc base alloy containing from .05 to 2% cadmium, from .05 to 1% nickel, from .1 to 2% manganese and from .005 to .5% lithium, substantially all of the balance being zinc. 

